The present invention relates to the fabrication and cleaning of components used in substrate processing chambers.
In the processing of substrates, such as semiconductor wafers and displays, a substrate is placed in a process chamber and exposed to an energized gas to, for example, deposit material on or etch features in, the substrate. During such processing, process residues are generated and deposited on internal surfaces in the chamber. In subsequent process cycles, the deposited process residues can “flake off” of the chamber surfaces and fall on the substrate to contaminate the substrate. Consequently, the deposited process residues are periodically cleaned from the chamber surfaces. In wet cleaning processes, the process residues are cleaned off the chamber surfaces by scrubbing or pressure washing the components with cleaning solutions between process cycles. Dry cleaning processes use a plasma of cleaning gas to clean the exposed portions of the components in the chamber. However, such cleaning processes increase chamber down-time to lower yields and increase capitalization costs. Thus, it is desirable to reduce cleaning cycles and increase the number of substrate processing cycles between cleaning cycles.
Forming a textured surface on the chamber components can reduce flaking-off of the process residues. The process residues adhere better to the textured surfaces thereby reducing residue flaking and/or allowing a larger number of process cycles to be performed between cleaning cycles. Such a textured coating can be formed, for example, by directing an energetic beam of photons, particles or molten material against the surface of component. However, the particles used to form the coating themselves become trapped in the depressions of the coating, and when subsequently loosened during thermal cycling of the process chamber or through exposure to the energized process gas, fall on and contaminate the substrate being processed in the chamber. The trapped particles can also reduce adherence of process residues to the textured component surface by blocking depressions and cavities in which the process residues would otherwise collect. Conventional methods of cleaning the textured surface include rinsing the component surface with chemical solutions, ultrasonically agitating the component, and passing nitrogen at a pressure of about (345 Kpa) 50 PSI over the component surface to remove entrapped particles from the textured surface. However, these methods often fail to remove all the lodged particles, and the components cleaned by these methods can provide reduced substrate yields during processing of the substrates.
The textured surfaces can also have particles, for example, of a coating material, that are loosely adhered to the component surface. The loose particles can be subsequently knocked off during processing of substrates to contaminate the substrates. In one method of removing the loosely adhered coating particles, the component is gently tapped to shake off the loose particles from the component. However, tapping does not always typically remove all the loose particles because a strong tapping force can damage the component. In subsequent process cycles, remaining loose particles flake off and contaminate the substrate. The tapping method also depends upon the operator and may not be consistently reproducible, with the results varying from one operator to another. Furthermore, excessive tapping force can structurally damage the coating and create even more loose particles.
Accordingly, it is desirable to have a method of cleaning chamber components, which removes undesirable particles from the components, such as entrapped particles and loose coating particles. It is further desirable to have a chamber component capable of processing a large number of substrates without undergoing cleaning and while reducing contamination levels. It is also desirable to have an efficient cleaning process that does not damage the component or its surface.